The USDA Zone info is a great tool for gardeners to help us figure out your gardening schedule. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

In Seattle you can determine when it's possible to plant polygonums by checking out the USDA zone info.

Planting Calendar for Polygonums

Frost tolerance for polygonums:	Not tolerant of frost.
When to plant:	After all chance of frost has passed.

You can not plant polygonums until after the last frost has passed because they require warm weather.

The earliest that you can plant polygonums in Seattle is April. However, you really should wait until May if you don't want to take any chances.

The last month that you can plant polygonums and expect a good harvest is probably August. Any later than that and your polygonums may not have a chance to really do well. You can get started a few weeks earlier by starting your polygonums indoors.

Last Frost Date

On average all chance of frost has passed is on March 15 in Seattle. You should expect an average low temperature of 15°F in the coldest months of winter.

Since the USDA zone info for Seattle is just an average the actual date of last frost will vary from year to year. Since half of the time in Seattle last frost occurs after March 15 be ready to cover your polygonums in the event of one of those late frosts.

USDA Zone Info for Seattle

Here is the info for USDA Zone 8b.

Average Date of Last Frost (spring)	March 15
Average Date of First Frost (fall)	November 15
Lowest Expected Low	15°F
Highest Expected Low	20°F

This means that on a really cold year, the coldest it will get is 15°F. On most years you should be prepared to experience lows near 20°F.

Plants to Grow in Seattle

You may be interested in your other planting guides for Seattle.